The difficulty of a language depends on many things. Native speakers of English can learn Spanish with less difficulty than Native Korean speakers, since English is closer to Spanish than Korean is.
On top of that some languages are considered easy to learn to speak, but difficult to learn to write and vice versa. An example would be Mandarin Chinese, from the perspective of Native English speakers it is considered easy to learn to speak, but difficult to read and write.
English is the hardest language to learn. :D
Croatian is a complex language and probably one of the most difficult language types on the world. You must be born in Croatia if you want to speak Croatian perfectly or govoriti Hrvatski savršeno.
It's not the most difficult language, but it's not the easiest either. Here's a true fact for you - the hardest language to learn on the entire planet, is English. And you're writing in English, so you have already mastered the world's most difficult language. There is nothing stopping you taking on German.
The language barrier is usually the most difficult aspect.
I can't imagine many disadvantages to learning English. English is one of the most prolific language in the world, with a lot of the major/most wealthy countries using it as their native language. It is however among the most difficult languages to learn.
Mandarin Chinese is the most spoken language in the world.
English is not the most spoken language in the world, the most spoken language in the world is Chinese since China is the biggest country in the world. English is the most easiest language to speak in the world but Chinese is the most spoken one.
English if not already learned
It is said that Mandarin Chinese is the most difficult language to learn after childhood, followed closely by English.
English is the most widely spoken language in the world.
The third most spoken language in the world is Spanish.
Mandarin is the most widely spoken language in the world.
Arabic is the most perfect language